Silicates Definition In the fields of geology and mineralogy, the term “silicates” refers to compounds whose crystal structure contains SiO4 tetrahedra. Silicates are either isolated or joined to form groups, rings, single or double chains, sheets, or three-dimensional frameworks.

Twinning Definition Twinning is the observed intergrowth of multiple crystals in a symmetrical fashion. This term applies to the examination of rock thin sections, in the field of optical mineralogy.

Geosyncline Geosyncline: In geology, a geosyncline is a large-scale indentation in the Earth’s crust that is filled with sediments. A geosyncline forms due to the gradual sinking of the Earth’s crust, causing sediment from adjacent areas to gather inside. An example of a geosyncline is the Appalachian Mountains.

Oblique-Slip Fault Oblique-Slip Fault: In geology, an oblique-slip fault is a fault that moves parallel to the strike or dip of the fault plane.

Rigidity Definition Rigidity – In geotechnical engineering and engineering geology, rigidity represents the ratio of the shear stress and the amount of angular rotation that it produces, within a rock sample.